Welcome to Medellin, coke capital of the world

In the outer office of the mayor of Medellin, a thickset bodyguard cradles a Remington pump shotgun in his arms. A revolver is shoved into the waistband of his trousers, and a two-way radio is recharging in a unit near his feet. Down the hall, only a whistle away, are more armed men. Outside city hall, a uniformed policeman shoulders an Israeli-manufactured Galil automatic rifle as he casts a careful eye on passersby.

Who said you can't fight city hall? For more than a decade, the drug barons of the Medellin cartel have been using murder and corruption in an attempt...